1. Field of the Invention
The present invention relates generally to an optical scanning apparatus and method and more particularly to an apparatus and method for linearizing the response of a mirror galvanometer to a reference signal.
2. Description of the Prior Art
Mirror galvanometers utilize a small mirror carried by a coil in a magnetic field. The mirror deflects a light beam incident thereon in a scan related to the amount of current flowing through the coil. The angle to which the light beam is deflected changes in response to small changes in the electrical current.
It is frequently desirable that the rate of scan of a galvanometer be linearly related to a small reference or driving current or voltage. Such a situation would be one where an instantaneously accurately positioned scanning light beam is sought for purposes of reading or writing.
In an ideal mirror galvanometer the current through the coil should cause mirror deflection in an amount linearly related to the magnitude of the coil current. However, because of such factors as non-uniform magnetic fields, variable galvanometer damping coefficients, such as those due to temperature effects caused by variable energy dissipation rates, self resonances within galvanometer systems, and the like, galvanometer mirrors do not deflect in a manner linearly related to the coil current.